1. Field of the Invention
The present invention relates to a printed circuit board and a manufacturing process thereof suitable for realizing higher wiring density.
2. Description of the Related Art
A printed circuit board of a laminated structure is formed by laminating a plurality of wiring layers in order to realize higher wiring density. Such printed circuit board is inherent for down-sizing of an electronic equipments.
In the meanwhile, when the printed circuit board of the laminated structure is manufactured with various resin materials having low dielectric constant without employing a reinforcement material, such as glass cloth or the like, several hundreds xcexcm of a laminated layer thickness is required in a single resin material of low dielectric constant in order to obtain a desired performance.
A thick laminated structure of the single resin material of low dielectric constant without reinforcement material is quite difficult to manufacture. In addition, by increasing layer thickness, mechanical strength is lowered.
The present invention has been worked out in order to solve the problem set forth above. Therefore, it is an object of the present invention to provide a printed circuit board and a manufacturing method thereof which can realize a thick film laminated structure of single resin material of low dielectric constant without reinforcement material.
According to the first aspect of the present invention, a printed circuit board is formed with an insulation layer of composite structure of a first resin material of low dielectric constant and a first general base material having different relative dielectric constants, and the insulation layer is disposed between conductor circuits.
The first base material may be stacked on a second general base material as a core material, the first resin material of low dielectric constant may be stacked on the first general base material, a first grounding conductor as the conductor circuit may be formed between the first and second general base materials, a plurality of conductive patterns may be arranged between the first general base material and the first resin material of low dielectric constant, and a line conductor as the conductor circuit may be arranged on the surface of the first resin layer of low dielectric constant.
The first general base material may be provided a thickness of several hundreds xcexcm and the first resin material of low dielectric constant is provided a thickness of several tens xcexcm. A second resin material of low dielectric constant may be stacked on the first resin material of the first resin material of low dielectric constant covering the line conductor, a third general base material may be stacked on the second resin material of low dielectric constant, a second grounding conductor is arranged on the third general base material.
According to the second aspect of the present invention, a manufacturing process of a printed circuit board comprises:
a first step of forming an insulation layer of a composite structure of a first resin material of low dielectric constant and a first general base material having different relative dielectric constants; and
a second step of interposing the insulation layer between conductor circuits.
The first step may comprise
a third step of stacking the first general base material on a second general base material;
a fourth step of stacking the first resin layer of low dielectric constant on the first general base material;
the second step may comprise
a fifth step of arranging a first grounding conductor as the conductor circuit between the first and second general base material;
a sixth step of arranging a plurality of conductor patterns between the first general base material and the first resin material of low dielectric constant; and
a seventh step of arranging a line conductor as the conductor circuit on a surface of the first resin material of low dielectric constant.
The first and third step may include an eighth process of forming the first general base material in a thickness of several hundreds xcexcm, and
the first and fourth steps may include a ninth step of forming the first resin material of low dielectric constant in a thickness of several tens xcexcm. The fourth step may include
a tenth step of stacking a second resin material of low dielectric constant on the first resin material of low dielectric constant covering the line conductor;
a eleventh step of stacking a third general base material on the second resin material of low dielectric constant; and
a twelfth step of arranging a second grounding conductor on the third general base material.
The conductor circuit may have a micro strip line structure or a balance type strip line structure.
In the printed circuit board and the manufacturing process thereof according to the present invention, the insulation layer is formed in composite structure of the first resin material of low dielectric constant and the first general base material having different relative dielectric constant, and the insulation layer is disposed between the conductor circuit to make the relative dielectric constant of the insulation layer of composite structure dependent on the value of relative dielectric constant of the first resin material of low dielectric constant.
The present invention will be understood more fully from the detailed description given hereinafter and from the accompanying drawings of the preferred embodiment of the present invention, which, however, should not be taken to be limitative to the invention, but are for explanation and understanding only.